Heat vegetable oil in a large skillet over medium-high heat. Add sliced onions and bell peppers, cooking until soft and slightly caramelized.
Push the vegetables to one side of the skillet and add thinly sliced steak. Season with salt, black pepper, and garlic powder. Cook for about 3-4 minutes until browned.
Lower the heat and place slices of provolone cheese over the cooked steak. Let it melt for about 1 minute.
Spread mayonnaise inside each toasted hoagie roll. Add shredded lettuce and tomato slices.
Scoop the cheesy steak mixture into each roll, pressing slightly to keep everything together.
Serve warm with a side of fries, onion rings, or a simple salad.